Hi, I've moved your thread to the medicine forum but left a link in the mature students forum as well
Hopefully some current/former medics can answer your questions and/or provide some insight into doing medicine as a mature student!
Some basic information that might be helpful though:
If you already hold a degree there are two potential options for earning a primary medical qualification: 1) there are accelerated graduate entry medicine (GEM) courses which are 4 years long, several of which accept any degree subject for your first degree, only open to graduates and 2) standard entry medicine which is a 5-6 year course applied to by school leavers and graduates. GEM tends to be a fair bit more competitive than standard entry medicine though.
In terms of financing, medicine is an exception subject so there is some funding from SFE available to pursue medicine as a second degree. Exactly what and how much depends on whether you are doing GEM or standard entry medicine. For GEM you should receive a maintenance loan in your first year, and partial tuition fee loan - you have to pay the first ~£3000 of the tuition fees yourself (although you could of course use some of the maintenance loan for that purpose). For standard entry medicine there is less funding available; for the preclinical years of the course (the first 3 or 4 years, I think it's 4 but not entirely sure) you are entitled only to a maintenance loan and have to self fund tuition fees. You could use the maintenance loan to pay the tuition fees if you agree a payment plan coinciding with the disbursement dates of the maintenance loan with your uni, and then support yourself with other sources of funding (e.g. work, savings, if you own property that might make things easier). In both cases for the clinical years (years 2-4 of GEM and I believe 5-6 of standard entry medicine) you will be funded by the NHS which is separate to SFE funding, and they will pay tuition fees and award a bursary I believe for those years.
In terms of entry requirements it might vary a bit depending on whether you apply to GEM or standard entry medicine and which GEM courses you do apply to if you go for that route. Some GEM courses have no requirements in terms of degree subject and I believe some do not require any particular A-levels, but instead require you take the GAMSAT which is I gather a very difficult exam covering material from A-level Biology/Chemistry/Physics and beyond (particularly I think the chemistry section extends to first year uni level chemistry). Others may require you take one or two A-levels at least in relevant science subjects, or equivalent - such as an Access to Medicine course. Note that "medicine with a foundation year" courses are normally only open to those meeting specified widening access criteria/contextual flags. The course for those with the "wrong" A-levels is "medicine with a gateway year".
However note also that since your A-levels were presumably taken some time ago, universities would generally probably expect to see some recent academic study (in the last three years typically). This could be satisfied by doing A-levels, an Access to Medicine course, or some OU credits. For the A-level route you could look into various distance learning providers, but be aware that medical schools generally (not currently due to covid) require the science endorsement i.e. that practicals to be taken. I gather it can be hard finding an exam centre that allows you to take these practicals and that they can be expensive as well. You may be able to get A-levels funded by an Advanced Learner Loan, but it depends on the provider. It's unclear whether the ALL covers the science endorsement as well.
The Access to Medicine route might be more straightforward in some respects, being a 1 year intensive course to prepare for applying to medicine (or dentistry/vet med sometimes), which can also be funded by an ALL (and as an Access course, if you subsequently complete a degree the ALL should be written off - although as it's a second degree, I'm not too sure). Note however not all medical schools accept all Access to Medicine courses. So if you are considering that route you should contact the medical schools you wish to apply to with details of the Access to Medicine course you are considering, including the provider of the course and the course units undertaken. Medical schools sometimes publish a list of acceptable Access to Medicine courses on their websites.
The OU option is less clear, and you should contact any medical schools to see if they would accept OU credits for entry, and if so if there are specific required modules you would need to take. I believe KCL accepts OU credits and lists the number of credits and modules expected on their entry requirements section.
Note also usually medical/caring work experience is essential for applying to medicine. Some GEM courses require quite extensive work experience in the NHS (I think one used to require ~6 months of full time work as a HCA or equivalent), and some Access to Medicine courses likewise expect you to have already gained relevant medical work experience before starting the course.
In terms of age I gather it's not uncommon to have older students studying medicine; by necessity all on GEM courses will have a degree and be usually 21 or older. Because GEM courses are quite competitive and it may take a couple of years of applying to get in, I gather the median age is usually a bit higher anyway.